Application of the AMBUR R package for spatio-temporal analysis of shoreline change: Jekyll Island, Georgia, USA Chester W. Jackson Jr. a,b,n , Clark R. Alexander b,c , David M. Bush d a Department of Geology and Geography, Georgia Southern University, Statesboro, GA 30460-8149, USA b Applied Coastal Research Lab, Georgia Southern University, 10 Ocean Science Circle, Savannah, GA 31411, USA c Skidaway Institute of Oceangraphy, 10 Ocean Science Circle, Savannah, GA 31411, USA d Department of Geosciences, University of West Georgia, 1601 Maple Street, Carrollton, GA 30118, USA article info Article history: Received 28 January 2010 Received in revised form 10 August 2011 Accepted 11 August 2011 Available online 1 September 2011 Keywords: Coastline GIS Program Movement Forecast Erosion Rate abstract The AMBUR (Analyzing Moving Boundaries Using R) package for the R software environment provides a collection of functions for assisting with analyzing and visualizing historical shoreline change. The package allows import and export of geospatial data in ESRI shapefile format, which is compatible with most commercial and open-source GIS software. The ‘‘baseline and transect’’ method is the primary technique used to quantify distances and rates of shoreline movement, and to detect classification changes across time. Along with the traditional ‘‘perpendicular’’ transect method, two new transect methods, ‘‘near’’ and ‘‘filtered,’’ assist with quantifying changes along curved shorelines that are problematic for perpendicular transect methods. Output from the analyses includes data tables, graphics, and geospatial data, which are useful in rapidly assessing trends and potential errors in the dataset. A forecasting function also allows the user to estimate the future location of the shoreline and store the results in a shapefile. Other utilities and tools provided in the package assist with preparing and manipulating geospatial data, error checking, and generating supporting graphics and shapefiles. The package can be customized to perform additional statistical, graphical, and geospatial functions, and, it is capable of analyzing the movement of any boundary (e.g., shorelines, glacier terminus, fire edge, and marine and terrestrial ecozones). & 2011 Elsevier Ltd. All rights reserved. 1. Introduction The movement of a shoreline, whether located adjacent to a stream, lake, or an ocean, is an expression of the processes that shape natural and developed landscapes. Operating across vary- ing spatial and temporal extents, natural processes govern the mobility of this land/water boundary over time. Within coastal regions, scientists and managers focus on mapping and quantify- ing the movement of the shoreline not only to gain a better understanding of these processes but also to determine potential impacts on coastal resources and to assist with policy-making decisions. Among the many questions researchers often want to answer when studying a given shoreline, there are four that are central to an analysis: (1) How far has the shoreline moved? (2) How fast did the shoreline move? (3) How variable is the shoreline’s movement? (4) Where is the shoreline going to be in the future? To answer these questions, researchers might use GIS software to either perform manual measurements or use auto- mated analysis tools to quantify distances and rates of shoreline movements and make forecasts. Over the past decade, the number of computer-assisted shoreline change analyses has increased as GIS software programs have become more accessible to researchers. Despite the wide availability of GIS software, there are still only a limited number of GIS-based tools dedicated to shoreline change analyses that are publicly available such as the Digital Shoreline Analysis System (DSAS) (Thieler et al., 2009), SCARPS (Jackson, 2004), and BeachTools (Hoeke et al., 2001; Zarillo et al., 2008). Furthermore, these tools require users to own a commercial GIS software license for ESRI’s ArcGIS (or the older ArcView v.3.x) to run them. The Analyzing Moving Boundaries using R (AMBUR) package for the R programming environment (R Development Core Team, 2011) provides a collection of scripts to assist with shoreline change analysis that takes advantage of R’s statistical, graphical, and geospatial capabilities, while allowing users the freedom to choose any commercial or open-source GIS software for editing, preparing, and viewing shapefiles. Although primarily intended for shoreline change analyses, AMBUR is able to analyze Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/cageo Computers & Geosciences 0098-3004/$ - see front matter & 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.cageo.2011.08.009 n Corresponding author at: Department of Geology and Geography, Georgia Southern University, Statesboro, Georgia 30460-8149, United States. Tel.:/fax: þ1 912 478 0174. E-mail addresses: cjackson@georgiasouthern.edu (C.W. Jackson Jr.), clark.alexander@skio.usg.edu (C.R. Alexander), dbush@westga.edu (D.M. Bush). Computers & Geosciences 41 (2012) 199–207